Eltrex Motion's plain bearings in the spotlight

Fundamental components

"Bearings are fundamental components in most types of industrial equipment and enable low-friction movements for operations such as positioning, transport, and load guidance. Users often take linear guides for granted because they are either hidden in the machine or have become so ubiquitous that we forget their value. In reality, they are essential for controlling movement," says Martin van den Berg, Product Manager Mechanical at Eltrex Motion.

Most linear guides use one of three types of linear bearings: plain bearings, roller guides, or ball bushings. Within each category of bearing types, there is a wide variety of design options and variations, offering unique advantages to engineers. In this article, we focus primarily on the plain bearing design and its strength in both common and unique applications.

Design

Plain bearings rely on sliding contact between softer bearing materials such as plastic, composite, or bronze, and a relatively harder guide material such as aluminum or steel. An important difference in the construction of plain bearings lies in the bearing liners. Some bearing manufacturers offer injection-molded plastic liners that are mechanically attached to the shell. These are generally inexpensive but need to be replaced more often. A second type of liner is made from a material containing polytetrafluoroethylene (PTFE). The Frelon liner is a combination of PTFE and fillers that is bonded to the inside of the bearing shell. The Frelon liner deposits a microscopic film on the shaft, fills in the valleys on the surface, and creates a Frelon-on-Frelon running condition that is considered true self-lubrication. Now, both plastic and Frelon are self-lubricating. However, various studies have shown that the Frelon liner demonstrates superior performance compared to injection-molded plastic liners when considering total wear and PV value.

Benefits of plain bearings

Plain bearings offer many of the housing features and options found in ball or roller bearings, including flanges, pillow blocks, and more advanced linear guides. Profiles for plain bearing systems can use a round shaft with round bearings, or a square or profiled rail with a corresponding square or profiled bearing. Plain bearings with Frelon liners offer many advantages such as:

• They absorb shock loads without damaging components.
• They excel in contaminated environments that are often harmful to linear ball bearings.
• Thanks to the self-lubricating bearing liner, no additional lubrication is required.
• They excel in wet or submerged applications.
• They are suitable for cleanroom or laboratory applications where wet lubricants cannot be used.

Read more?

Read the entire article (in Dutch) in the online magazine Aandrijven & Besturen.